Newbie requires direction, please

[alexlyf]

Hi guys,

Sometimes ago I was browsing a forum of home-built cockpit for flight simulator and get me interested in making panels and name tags. So I start my research and found this forum, what a great surprise! I am completely new to this DIY CNC community and found the projects here absolutely fascinating!

My work provides me some knowledge for working with PLC programming and stepper motors, however, I am a total noob in mechanical machinery. I have basic knowledge on CAD but that’s it, I don’t even know what G-Code is.

My final goal is to build a CNC machine for making name tags and panels engraved with lines and texts. I also want the machine be able to engrave on 2 ply plastic, wood, aluminum or even stainless steel (not sure if this is possible though) of size up to 24" x 24".

What I need is some direction pointers to help me understand about the controls and the way CNC works. It would be great if someone can explain a bit on how to start from using a dxf file to the final production. Oh and I plan to use open source software for I am such a cheap bastard. Hehehe. BTW, I would like to keep the plan budget under $1000.

Thank you for any help in advance.

Cheers,
Alex

[Mi-Hoen]

Hi,

What you want to do is: recearching. i'm currently at the end of my research and have just began buying parts. I'll write a little something, hopefully it gives you some inspiration (Y)

if you want to cut alluminium, plastics, wood you have to considder that you need the STIFFEST construction possible. hard materials like aloys need more cutting power then for instance plywood. the more force your machine is facing the more deflection (play, bending, vibrating parts) will apear between the parts, wich results in ''less'' accuracy.

*i'm building a router out of MDF and aluminum extrusion. the y-axis are 80cm long, the x-axis is 57cm long and the z-axis is 24cm long. i keep the device small. i'm not into ''big'' projects ($$$ ), the resulting cutting area will be aproximatelly A2 papersheet size.

when you use short and thik material the chance of deflection is smaller then long parts with the same diameter. i have chosen to use 20mm, round linear bearings. these are EXPENSIVE (+/- 20 bux ea, u need at least 8, max 12pc.) the 20mm axes (roled, silversteel or carbonsteel) are alot cheaper then for instance rails made by THS (search ebay) these rails and bearings can take massive loads. but is this nessesairy in a DIY router? if you can get them cheap, get them, no doubt. don't buy them brand new, it'll hurt your wallet.

i've ordered some 10mm thik alu plate material from the factory (just like the extrusion, cut by a ''good'' saw, so perfectly 90* in al directions) there has to be alot of work to be done on the metal parts. i have to make bearing houstings, ax-holders, ballscrew/nut holders, motor mounts etc.

for the movement we got these nice parts available search for : leadscrew, ballscrew, spindle, acme, trapzium. there are alot of price categories. on ebay you can find alot of stuff you could use, for a nice price.

*don't concentrate on the maximum resolution of the leadscrew, remember that the motors have optimum holding torgue at low RPM. wich results in a strong, (relatively)slower machine capable of cutting dense material.

you should get some 200oz/in + steppers. you need some overkill in matters of force. you want to have a nice and stable power supply. the higher the voltage (example: 12VDC versus 32VDC) the more power your motor will have at higher RPM. wich can be nice.

you want to buy some nice microstepping drivers. i'm getting a cheap one. has a max of 1600 microsteps/REV. good enough for my first machine!

i hope i will be able to cut alluminium right away! if not, it'll happen on a later stage (when the money starts roling again, lol)

i'm going to use a KRESS 800 power drill, it has 800Watt and has double bearings to prevent flexing while there are forces on the spindle. try to find something similar. a variable RPM is very handy! saves up alot of bits :P

well, i think youll be good for the weekend ^_^ Keep it simple, and diy all the way (Y)

here a sketch of my design.



greets,

Mi, holland!

[Den-Den]

You are on the right track. Keep reading and looking at other people's machines. The trick to cost effective DIY machines (not just CNC) is to design around what you have. This refers to materials, tools and knowledge. A lot of any one of these can party make up for a lack of another. My machine is a little smaller than your specs, it cuts wood / plastic fine. I am working on an upgrade to stiffen the "Y" axis that should allow me to cut aluminum. Cutting stainless steel is a big ambition.

[jcc3inc]

Alexlyf,

If you will email me I'll send you pix of a small machine which I made.
It is a test bed, rack and pinion drive.

jccinc-at-owc-dot-net